Transcript Croatia

26th EWGLAM & 11th SRNWP meetings
4th - 7th October 2004,Oslo, Norway
Zoran Vakula, Lovro Kalin, Martina Tudor and Stjepan Ivatek-Šahdan
Meteorological and Hydrological Service, Grič 3, HR-10000 Zagreb, Croatia
[email protected], [email protected], [email protected] & [email protected]
Operational ALADIN forecast in
Croatian Meteorological and Hydrological Service
Verification
Skill scores for probability of precipitation made of ranked
probability scores of quantitative ECMWF and ALADIN
CROATIA precipitation forecasts for "1st" and "2nd" day
for Zagreb Maksimir (14240), from summer 1997 to
summer 2004 (left).
Bias of ALADIN CROATIA precipitation forecast (rain
versus no rain) for Zagreb Maksimir (14240), Gospic
(14330) and Split Marjan (14445) for year 2003 (below
left).
Mean errors and standard deviation of ALADIN CROATIA
wind speed for Split Marjan for the year 2003 (below).
In the Croatian meteorological service ALADIN is operationally run twice a day, for 00 and 12 UTC. Coupling
files are retrieved from ARPEGE (Meteo-France global model) via Internet and RETIM2000. Model resolutions
are 12.2 km for LACE domain, 8 km for Croatian and 2 km for the high-resolution dynamical adaptation domains.
The execution of the suite is controlled by the OpenPBS (Portable Batch System) as the queuing system.
Horizontal resolution of the LACE domain is 12.2 km, 37 vertical -levels, time-step 514 sec, 229x205 grid points
(240x216 with extension zone). Corners: SW (34.00,2.18), NE (55.62,39.08).
Horizontal resolution of Croatian domains is 8 km, 37 vertical -levels, time-step 327 sec, 169x149 grid points
(180x160). Corners: SW (39.00,25), NE (49.57,22.30).
Initialisation of ALADIN on LACE domain is provided by Digital Filter Initialisation (DFI). Coupling frequency and
frequency of output files for the LACE and Croatian domains are 3 hours. When the 48 hours forecast on LACE
domain is finished 48 hours forecast for Croatian domain starts without initialisation with coupling files from
LACE.
6 domains for the dynamical adaptation of the wind field in the lower troposphere to 2-km resolution orography
for mountainous parts of Croatia. Dynamical adaptation is run sequentially for each output file, with 3 hour
interval. In the dynamical adaptation meteorological fields are first interpolated from input 8-km resolution to the
dynamical adaptation 2-km resolution. The same file is used as a initial file and as a coupling file that contains
boundary conditions for the model.
Visualisation of numerous meteorological fields are done on LINUX PC. Comparison of forecasts with SINOP
data are done hourly for today's and yesterday’s forecast. The products are available on the Intranet & Internet.
Internet address with some of the ALADIN products, total precipitation and 10 m wind:
http://prognoza.hr/aladin_prognoza_e.html & http://www.dhmz.htnet.hr/prognoza/aladin_prognoza_e.html.
PBL height determination
Operational version of ALADIN used in Zagreb is AL25T1_op2.
PBL height is diagnosed using modified formula of Ayotte (1996)
where PBL height is determined using virtual potential temperature
vertical integral. If the value at the level z is significantly larger than
ts vertical integral value between this level and the ground, PBL
height is detected. However, as can be seen in the top figure on the
right, using this formula, PBL height is detected very low in
statically stable situation. The significant drawback of this method is
that the effect of wind shear on dynamical stability is neglected.
The virtual potential temperature profile is modified to include wind
shear impact on stability. The value at surface remains the same,
above it, the values are modified by wind shear.
The new values of virtual potential temperature are used in the
integral. First the deviation between the level value and the integral
value of the virtual potential temperature is calculated.
The contribution of this layer to the PBL height is calculated.
Root-mean-square errors of maximum temperature for day 1 (left) and day 2 (right) forecast of ALADIN
LACE and CROATIA for direct model output and model output statistics, for Zagreb Maksimir (14240), from
summer 1997 to summer 2004 (top row) and the last two years (bottom row). MOS are are done using
regression equations (y=ax+b) which were calculated from historic data for warm (April to September) and
cold (October to March) part of the year.
These values are summed up to the level where PBL top is detected. If the wind on the lowest model level is strong, the
diagnosed PBL height are high. In statically stable situations with weak wind, the diagnosed values are low. The vertical
integral makes the method robust to oscillations the model variables might have in the vertical. The figures show
forecasted PBL height before (left) and after (right) the wind shear impact introduction.
Adriatic storm case
• On 24th March 2004 03 UTC a cyclone
Du
Du
Gr
Bi
stroke a southern part of Croatian coast
in the Dubrovnik area. Unfortunately, the
movement was forecasted too fast and
the depth of this cyclone was severely
underestimated.
Comparison
of
the
forecasted mean sea level pressure with
12-km (red) and 8-km (orange) with
measurements from the SYNOP (violet)
stations
pressure
(below).
forecast
Mean
sea
(below
left)
level
and
analysis (below right) for 00 UTC 24th
March 2004.
Seasonal (top row) and monthly (bottom row)
mean errors, mean absolute errors, root-meansquare errors and skill scores (according rootmean-square error and regression persistency)
for day 1 (left) and day 2 (right) maximum
temperature forecast of ALADIN LACE and
CROATIA for direct model output, for Zagreb
Maksimir (14240), from January 2003 to august
2004.
Left: The same like above, but for the day 2
minimum temperature forecast.
Bi
Bi Gr
Du
Gr
Du